The present invention relates to a semiconductor device including a semiconductor element which may change in characteristics upon exposure to light.
As examples of a semiconductor element which may change in characteristics upon exposure to light, a MOS transistor, a nonvolatile memory including a floating gate electrode, and the like can be given. These semiconductor elements are exposed to light especially when mounted using a COG mounting method such as bare chip mounting. As a result, on/off characteristics may be changed in the case of a MOS transistor, or electrons injected into the floating gate electrode may be removed in the case of a nonvolatile memory. In order to prevent such a change in characteristics of the semiconductor element, a shading layer for preventing application of light is provided above the region in which these devices are provided.
A technology using the shading layer is disclosed in Japanese Patent Application Laid-Open No. 11-288934. In Japanese Patent Application Laid-Open No. 11-288934, two shading layers which cover the semiconductor elements are provided at different levels, and these shading layers are connected through a contact layer.
However, since it is impossible to sufficiently shade light merely by providing the shading layers above the shading target region, it is necessary to form the shading layers so as to widely cover the surroundings of the shading target region in order to increase the shading effect. Therefore, the area of the shading layer cannot be reduced, and a reduction in size of the semiconductor device may be hindered. In the case where the area of the shading target region is large, the shading target region may not be covered with a single shading layer due to design rule limitations.